#include<stdio.h>
void main()
{
    long s,n,k,i;
    scanf("%ld",&n);
    k = 2*n-1;
    s = 0;
    for(i=1;i<=k;i+=2){
        s += i;
    }
    printf("1+3+...+%ld=%ld\n",k,s);
}